Embracing repetition

Before we get much further, I think it's important to deal with a possible elephant in the room. I need to try and convince you that eliminating repetition of properties and values across files may not buy as much, from a maintenance perspective, as a solid and contained set of modules that are easy to remove from a codebase as needed.

The ECSS approach embraces repetition of properties and values in the CSS.

With ECSS, every single visual module or component is written with a micro-namespace to provide isolation from other modules and components. Here is a typical example of an authored ECSS rule (the authoring syntax is very similar to Sass, but typically facilitated by PostCSS):

.ip-SubHeader_Wrapper {
    @mixin Headline;
    align-items: center;
    /* We want the subheader hidden by default at the
    smallest sizes */
    display: none;
    font-size: $text12;
    background-color: $color-grey-54;
    border-bottom: 1px solid...